Electronic devices having cameras are often equipped with a flash that may trigger a pre-flash. A pre-flash is a light pulse fired before a regular flash is generated and an image captured. The pre-flash may be used to reduce a red-eye effect in the captured image or to estimate the proper flash power and exposure settings to ensure the captured image is properly exposed. More specifically, the pre-flash may be triggered and pre-flash data obtained, possibly in the form of a temporary image. Using the pre-flash data, various settings may be determined that are to be used for the camera when obtaining the captured image. For example, a focus point may be determined, a white balance value may be set and/or an exposure to be used to obtain the captured image may be set.
The pre-flash is typically designed to be brief in duration in order to minimize power consumption and also to enrich the user experience. Typically, when pre-flash is used to acquire a single temporary image which is used to determine the camera settings, far objects will appear under-exposed and close objects will appear over-exposed. This can make it difficult to estimate the camera settings, such as the exposure settings.
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